Muharram literally means ” Forbidden” . It is one of the four sacred months during which waging a war and fighting is not allowed.
Allah says in the Holy Quran:
“Surely the number of months with Allah is twelve months in Allah’s ordinance since the day when He created the heavens and the earth, of these four being sacred; that is the right reckoning; therefore be not unjust to yourselves regarding them, and fight the polytheists all together as they fight you all together; and know that Allah is with those who guard (against evil)Postponing (of the sacred month) is only an addition in unbelief, wherewith those who disbelieve are led astray, violating it one year and keeping it sacred another, that they may agree in the number (of months) that Allah has made sacred, and thus violate what Allah has made sacred; the evil of their doings is made fairseeming to them; and Allah does not guide the unbelieving people.”[Surah 9 :Taubah, Verse 37- 37]
The month of Muharram is one of the four sacred months of the Islamic calender as mentioned in the hadith of our Prophet Muhammad saw narrated by Abu Bakra ra:
“The year is of twelve months, out of which four months are sacred: Three are in succession Dhul-Qa’ da, Dhul-Hijja and Muharram, and (the fourth is) Rajab of (the tribe of) Mudar which comes between Jumadi-ath-Thaniyah and Sha ban” [Bukhari Vol 004, Book 054, Hadith 419]